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Lead(II) oxalate is an organic compound with the formula PbC2O4. It is naturally found as a heavy white solid.[2]

Preparation

This compound is commercially available. It may be prepared by the metathesis reaction between lead(II) nitrate and sodium oxalate:[3]

Pb2+(aq) + C2O42− → PbC2O4 (s)

A dihydrate may be formed with water solutions. But the dihydrate dehydrates in air:[4]

(PbC2O4•2H2O (s) → (PbC2O4 (s) + 2H2O (g)


The trihydrate (PbC2O4•3H2O) can be made by reacting a solution of lead(II) carbonate in perchloric acid with oxalylhydroxamic acid.[5]

Properties

As well as an anhydrous form, a monohydrate (PbC2O4•H2O),[5] a dihydrate (PbC2O4•2H2O) and a trihydrate (PbC2O4•3H2O) are known. The dihydrate is from the orthorhombic crystal system, with space group Pnam (number 62), with unit cell dimensions: a = 9.053 Å b = 8.036 Å and c = 7.834 Å. The unit cell volume is 569.8 Å3 with four formula per cell, giving a density of 3.860 g/cm3[4]

The trihydrate has triclinic crystals with space group P1 and unit cell dimensions and angles: a = 6.008 Å, b=6.671 Å, c=8.493 Å, α=74.70°, β=74.33°, and γ=80.98°. The unit cell volume is 314.41 Å3 with two formula per unit cell. Density is 3.69 g/cm3.[5]

Solubility

Lead(II) oxalate is insoluble in water. Its solubility is increased in presence of excess oxalate anions, due to the formation of the Pb(C2O4)22− complex ion.[6]

References

  1. ^ "Lead(II) Oxalate". Chemistry Reference. http://www.chemistry-reference.com/q_compounds.asp?CAS=814-93-7.
  2. ^ "Lead Oxalate". American Elements: The World's Manufacturer of Engineered & Advanced Materials http://www.americanelements.com/pboxl.html.
  3. ^ Grases, F.; Ruiz, J.; Costa-Bauzá, A. (1993). "Studies on Lead Oxalate Crystalline Growth". Journal of Colloid and Interface Science. 155 (2): 265–270. doi:10.1006/jcis.1993.1035.
  4. ^ a b Boldyreva, E. V.; Naumov, D. Y.; Podberezskaya, N. V.; Virovets, A. V. (15 November 1993). "Structure of lead(II) oxalate dihydrate". Acta Crystallographica Section C: Crystal Structure Communications. 49 (11): 1882–1884. doi:10.1107/S0108270193004652.
  5. ^ a b c Sheng-Hua, Huang; Ru-Ji, Wang; Mak, Thomas C. W. (April 1990). "Crystal structures of isomorphous cadmium(II) and lead(II) oxalate trihydrates". Journal of Crystallographic and Spectroscopic Research. 20 (2): 99–104. doi:10.1007/BF01160959.
  6. ^ Kolthoff, I.M.; Perlich, R. W.; Weiblen, D. (1942). "The Solubility of lead Sulfate and of Lead Oxalate in Various Media". Journal of Physical Chemistry. 46 (5): 561. doi:10.1021/j150419a004.
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